This invention relates to electrical connectors and, in particular, to apparatus for retaining one or more contact terminals in an insulation body without the necessity of incorporating a separate retention member for each contact terminal.
Structural connector designs which may be inserted into the bore of an insulation block from the rear face and locked in the bore against axial movement in either direction and which are then removable by the insertion of a tool into the entry location to withdraw the electrical connector are known in the art. For example, such a connector system is disclosed in U.S. Pat. No. 3,158,424, filed July 25, 1961, in which a sleeve insert having a retaining clip is inserted into the insulation body passageway with the contact terminal, either a jack or a plug, being held in place in the insulation block passageway by the sleeve insert clip. While the clip in this invention could be moved upward thereby allowing the connector terminal to be withdrawn and replaced, this connector device required a separate sleeve insert which was a third element thereby complicating the assembly procedure and increasing the expense.
Similarly functioning clip mechanisms are disclosed in U.S. Pat. Nos. 3,335,396 and 3,028,574, each requiring a separate clip member similar to that disclosed in U.S. Pat. No. 3,158,424 discussed above. By contrast, the present invention requires no such clip portion and, indeed, does not require a separate sleeve insert or any other insert or clip since the retaining function is integrally incorporated as a part of the contact terminal itself in cooperation with a shoulder portion in the insulation body passageway.
In U.S. Pat. No. 3,396,364, an electrical socket member is disclosed which has an intermediate portion which is deformed in such a way that a resilient deformation occurs upon the insertion of a pin to provide a strong electrical contact. One embodiment of this invention discloses an end portion having a first generally circular edge and a second generally elliptical edge connected by a continuous surface to define a generally conical form. As the circular edge is inserted into the passsageway in the insulating block, the continuous surface is disclosed as being generally and progressively deformed to assume the shape of the circular front edge along the entire length until the rear edge passes a shoulder whereupon the rear edge springs back to its original elliptical form with the rear edge abutting against the shoulder preventing the contact from being withdrawn from the passageway. Although this apparatus allows the elimination of a separate sleeve incorporating a clip, the configuration shown still requires a third cylindrically shaped part which must be affixed to the end of the connector socket. Thus, even though the clip is eliminated, the referenced device would still require an additional part and would thus entail many of the problems of fabrication previously encountered.
In addition, the device disclosed in the above patent requires that the connector between the end section and the socket portion be reinforced and made strong so that the end portion would not detach from the socket portion allowing the socket portion to be removed from the passageway and the insulator block. Clearly, such a junction between the end portion and the socket portion would be effected by the continual deformation from an elliptical to a circular cross section as the pin was inserted and removed. Such a flexing motion would amplify the possibility of the head coming loose and thereby causing electrical contact to be broken.
It will also be appreciated that in the configuration of the above-disclosed reference, the contact terminal is rear insertable but can only be released by inserting a tool in the front and then pulling the connector through the rear of the insulating block. By contrast, the present invention is rear insertable and rear releasable without the necessity of accessing the front of the connector thereby facilitating removal of individual contact terminals.
Yet another distinction between the present invention and the cited reference is that the cited reference described an insert cavity configuration having a front and rear diameter larger than the center diameter with the clip action being in the front diameter after passing through the rear and center diameters. In such a scheme, the clip area is exposed. By contrast, the present invention has a front and rear diameter which is smaller than the center diameter with the spring section of the contact being completely housed in the center section. Thus, the spring or clip section of the contact terminal is not exposed after insertion.
Still another distinction is that the present invention may be made of a single member by simply permanently deforming one end of a tubular structure to assume an elliptical shape. The member is then made of a material which can be resiliently deformed to assume a circular shape as it passes through a circular passageway in the insulating block and thereafter returns to the elliptical shape when the deformed portion is in place in a central larger diameter circular passageway portion. The primary purpose of the disclosed connector in the above reference is to provide a tight electrical contact by collapsing the circular connector portion to two substantially parallel sections adjacent to one another to provide a spring action when a male plug is inserted between the two sections. To provide such a jack function and at the same time, with the same tubular member, provide elliptical cross section immediately next to the collapsed portion as in the present invention would be difficult, if not impossible. Even if possible, however, the resultant connection would be very difficult to insert and even more difficult to remove from the insulation passageway.
Finally, because the insertion of a mating member causes the elliptical edge portion at the ends of the major diameter to be pushed against a shoulder, no abutment portions are required in the present invention as is required by the embodiment disclosed in the above-identified reference, since in that case the insertion of a pin (at least in one direction) causes the edge portions at the ends of the major axis of the elliptical edge region to be pushed away from the shoulder portion. In view of these substantial differences, it is clear that the above-cited reference not only does not disclose the present invention but teaches away from it. The present invention thus provides a novel and advantageous advance in the art of contact terminals and electrical connectors and, in particular, provides a simplified, less expensive and more reliable connector assembly than those previously provided and, in particular, than that provided by U.S. Pat. No. 3,396,364.